https://svn.boost.org/trac10/ticket/4996 <p> I have bug in function is_lower. <em> Kubuntu 10.10 x32 gcc 4.5 </em></p> <p> std::string str ="hello world";<br /> std::cout &lt;&lt; str &lt;&lt; " " &lt;&lt; (boost::all(str,boost::is_lower()) ? "is " : "is not") &lt;&lt; " written in the lower case" &lt;&lt; std::endl;<br /> </p> <p> <em>hello world is not written in the lower case<br /> ????? </em></p> en-us /htdocs/site/boost.png https://svn.boost.org/trac10/ticket/4996 Trac 1.4.3 Steven Watanabe Fri, 17 Dec 2010 16:38:50 GMT https://svn.boost.org/trac10/ticket/4996#comment:1 https://svn.boost.org/trac10/ticket/4996#comment:1 <ul> <li><strong>status</strong> <span class="trac-field-old">new</span> → <span class="trac-field-new">closed</span> </li> <li><strong>resolution</strong> → <span class="trac-field-new">invalid</span> </li> </ul> <p> You're asking whether every character in the string "hello world" is a lower case character. A space is not a lower case character, thus the result is false. </p> Ticket